The use of electronic books, such as electronic textbooks, has increased significantly in recent years. A person (e.g., a student) using the electronic book may want to create supplemental content, such as note cards and/or quizzes, to help improve or test the person's understanding of the content in the book.
But existing methods for generating supplemental content are cumbersome and inefficient. In addition, existing methods take longer than necessary, thereby wasting energy. This latter consideration is particularly important in battery-operated devices.